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Basketane is a polycyclic alkane with the chemical formula C10H12. The name is taken from its structural similarity to a basket shape. Basketane was first synthesized in 1966, independently by Masamune and Dauben and Whalen.
An alternative synthetic route with better overall yield uses 1,4-benzoquinone and cyclohexa-1,3-diene as starting materials. 1,4-Benzoquinone ( 1) is first converted to 2,5-dibromo-1,4-benzoquinone ( 2), which reacts in a Diels–Alder reaction with cyclohexa-1,3-diene ( 3) to form the polycyclic diketone 4. This diketone photoisomerizes to 1,6-dibromopentacyclo6.4.0.03,6.04,12.05,9dodeca-2,7-dione ( 5), which undergoes a pseudo-Favorskii rearrangement in a 25% aqueous solution of sodium hydroxide, giving the dicarboxylic acid 6. The acid is decarboxylated with a modified Hunsdiecker reaction to a dibromide 7, which is reductively debrominated with tributyltin hydride to basketane ( 8) at a 11% yield relative to the starting material cyclohexa-1,3-diene.
A 1994 synthesis starts with homocubanone, a cubane derivative, forming basketane via the basketyl radical. The synthesis functions by forcing cubane rings to be opened up via structural strain to create the chemical bonds necessary for this rigid molecule. This method is known as ring expansion where one part of two conjoined ringed are opened and rearranged to remove barriers between the two ring systems.CyclobutaneMethyl group radicals that rearrange and open into structures such as basketane and cubane are favorable rearrangements with free energy barriers around 0.3 kcal/mol.
Other transition metals catalyze the formation of a snoutane derivative with a tricyclic diene. The ratio of the products depends on the nature of the catalyst used and the substitutions on the basketane.
Basketane absorbs an equivalent amount of hydrogen gas in the presence of palladium on carbon, After some initial confusion, it was shown that the C3-C4 bond is hydrogenolyzed to give the dihydrobasketane tetracyclo4.4.0.02,5.03,8decane. Further hydrogenation cleaves the C5-C6 bond to give the hydrocarbon twistane.
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